Just took the car out for a drive again to get lunch, 10 minutes away. Still had very firm shifts. Parked it, went inside to get some seafoam trans tune, dumped that whole bottle in, went out for a drive, and now the shifting is back to normal, but 1st gear slips badly. It almost doesn't want to engage. You have to feather the throttle to get 1st gear to catch on, and then its fine.

Are these signs that the pressure control solenoid is going bad?

IMO, pulling some specific values from the same car it came from(or another like it) would be a good idea....

There'* a TSB out according to Bob that also references a 1-2 clutch being bad that could be the source of the problem, or the PCS solenoid being weak or bad.

Got an update.



I went to a transmission shop and they pulled a code: P0748 - pressure control solenoid electrical. They tried to convince me that the sprag assembly is broken and that'* why it doesn't engage first gear. The clutch pack isn't bad because if it was, the clutches would be burning against each other and my fluid would smell. It does not smell.



And here'* more.



If I manually downshift into 1st gear when slowing down and coming to a stop, at exactly 14mph, every single time, the car will give a somewhat harsh jolt engagement into 1st gear. I don't like the fact that its harsh, but I do like the fact that it engages, and when I accelerate from that stop, I have perfect gear engagement and can roast my tires all day long. If I know I'm going to come to a complete stop, and I downshift into 1st gear after I've already stopped, I will have 1st gear when I accelerate again.



Most of the time, if I don't do this, the revs just climb when I try to accelerate and I don't have much of a first gear at all. The trans ends up revving up to where 2nd gear would shift, and that'* how I would accelerate before.



And, when the car is cold (which it hasn't been since this morning), it will engage all gears perfectly, although rather harshly.



So now what could it be? Its at least driveable now that I can get 1st gear manually.

Might also be worth mentioning, when the shifter is in the 1st gear position, it will upshift into 2nd perfectly, which at light throttle is around 2500rpm for me. The regal'* old 4T60E used to stick in 1st gear and climb all the way up to 5000 before letting off on its own and into 2nd gear.

Just looked back at the description for this transmission from the place I bought it:



Run tested – shifts smooth, NO noises or slipping!

Drained of fluids and inspected to be free of internal wear or damage

Complete with matching Torque Converter (if applicable)

Professionally and carefully removed from the vehicle

Steam cleaned to remove external grease & dirt

Securely strapped to a pallet and ready for shipping



If they did indeed drive the car and not just pull the trans and sell it (which would be stupid), then the problem really is on our end, perhaps in the tune, the wiring, or who knows what. The simple truth is that the transmisison works perfectly if you manually select 1st gear as you're slowing down and hold it there until you're ready to shift past 2nd.



I also discovered that the transmission came with a 6 month parts-only warranty. The guy I talked to about this transmisison before I bought it said that the car was driven, albeit only on the street in 1st and 2nd gear since it had rear end damage, and said it was fine. I'm pretty sure they would have noticed it failing to engage like this.

Reading this thread makes me think its the PCS:

http://60degreev6.com/forum/showthre...agement-(4T65E)

The PCS is a know weak link in these transmissions. Have you have a oil pressure test done?

Haven't had an oil pressure test done, but supposedly a code would come up for having low pressure?

Bob thinks he knows why this all isn't working. He suggested that I test the wiring from the trans plug to the PCM, since it is a junkyard harness, and to make sure that all the leads are in the right places and not pushed out or anything, so I'll try that first, and if all else fails, looks like I'll need a new PCS.

I have a local guy with that code, have read the fsm many times, consulted with Steve and Dave etc etc.

P0748 is a pcs electrical issue code. You need to check the wires from the pcm to the connector at the trans for continuity. Then ohm out the wires at the trans connector and see what readings you get. At about 190F, IIRC the reading should be 6-8 ohms.

With this code set, your pressure should be maxed out. This is the reason why you are getting ..."firm" shifts.